1. Field of the Invention
This invention relates to a method of treating or handling liquids and more particularly to a method for treating radioactive liquids such as wastes containing radioactive material.
2. Description of the Prior Art
The treatment, handling and disposal of liquid industrial wastes is a problem which has become increasingly more important in recent years due to the quantity of wastes generated and, significantly, the increasing awareness of the deterioration of our environment. Much new technology has been developed in this area but it is expected that further improvements will be necessary to maintain and improve the quality of the environment, and increasingly stricter governmental regulations will require better means for treating, handling and disposing of liquid wastes. Considering the increasing use of nuclear power as a primary source of energy, and the nature of the wastes derived from such plants, the need for reliable and economically feasible methods for treating, handling and disposing of such wastes becomes evident. Special techniques are necessary and numerous safety problems are presented in treating, transporting and disposing of radioactive materials.
Liquids containing radioactive materials are usually derived from several sources, and as used herein, the term "radioactive liquids" is intended to include any liquid containing any radioactive material in a broad sence. Normally as understood by persons skilled in the art, a radioactive liquid is a liquid vehicle such as water and/or an organic solvent containing radioactive solids dissolved and/or suspended therein. More particularly, in the disclosed embodiments of the invention which follow, it refers to liquids such as water containing radioactive materials or elements formed as by-products in nuclear energy processes or formed in the cleaning, etc., of nuclear reactors. The term radioactive liquid is meant to also include high solid content fluids; i.e., sludges and semi-solids. It is not intended to limit this invention to a particular type of radioactive liquid.
Such radioactive liquids are typically and predominantly composed of water with a very small amount of solid matter dissolved and/or suspended therein. Such liquids may also contain significantly amounts of organic or other liquids. It is difficult to remove the radioactive material from the liquid and, of course, the liquid may not simply be disposed after such removal since it may still contain a small amount of radioactive material and hence even the liquid after removal of most of the solid radioactive material still retains a substantial amount of dangerous radioactivity.
The liquid vehicle, generally water, may be evaporated as is taught in the prior art prior to treating the radioactive material. However, where a large quantity of radioactive liquids is generated, very large and expensive evaporators are necessary to remove the water prior to treatment of the solid radioactive material, and the process may become prohibitively expensive. There is a need therefore for a simple, efficient and inexpensive process for treating and disposing of radioactive liquids.
Various processes are known for treating and disposing of radioactive liquids such as wastes. For example, U.S. Pat. No. 3,298,960 discloses a method for the disposal of waste solutions containing dangerous substances such as poisons or radioactive wastes by the addition of a gel forming material to the waste bearing solutions to partially solidify the waste solutions thereby facilitating handling and disposal. The gel products are formed by the addition of sodium silicate or formaldehyde to certain metal cleaning waste solutions derived by the application of the metal cleaning solutions to inaccessible metal surfaces of nuclear reactors.
French Pat. No. 2,015,010 discloses a method of concentrating aqueous solutions or suspensions of radioactive wastes by first concentrating the solutions by a known method and then solidifying the concentrated solution by mixing the same with a synthetic polymerized alcohol such as polyvinyl alcohol, followed by drying to cause hardening of the alcohol to render it water-insoluble and to reduce the initial volume of the alcohol and solution.
U.S. Pat. No. 3,142,648 discloses a process for the production of solid products containing radioactive waste material. After the formation of an aqueous mud such as by removing as much of the liquid contained therein as possible, generally water, the process involves mixing the mud with a fluidified bitumen in the presence of a surface active or wetting agent which serves to permit coating of the mud and to facilitate separation of any water contained therein. The greater part of this water is then eliminated by decantation or other means and the resulting bituminous mass is further mixed at a temperature such that it becomes sufficiently fluid and is finally poured in order to obtain, on cooling, solid blocks of suitable plasticity.
U.S. Pat. No. 3,838,061 discloses a method of packaging radioactive waste products which have previously been converted to dry powder form, by incorporating the powder in a resin which is polymerizable at room temperature followed by copolymerizing the resin with a monomer to obtain a solid material. The powdered radioactive waste is obtained by, for example, subjecting a solution thereof to evaporation.
U.S. Pat. No. 3,463,738 discloses the conversion of radioactive organic liquids into a solid form by homogeneously mixing liquid polyethylene with the radioactive liquids and then cooling the resulting mixture to form a solid, essentially nonporous, rigid polyethylene body which effectively contains the radioactivity.
Other prior art processes for decontaminating or containing radioactive wastes are disclosed in U.S. Pat. No. 3,262,274 and in U.S. Pat. No. 3,896,045.